That used to happen - still does occasionally - with Maggie. It broke my heart - I'd come home to find everything EXACTLY the way I'd left it in the morning - she wouldn't touch her food, water, toys, etc. They get used to you being gone eventually. I've signed Maggie up for daycare 3 days a week - one of those days includes obedience training which is a bonus! The daycare has definately helped with the anxiety she experiences when we're gone all day at work. It helps me too because I HATE being away from her!
Can you get a dog walker to come a couple times a week to break up the long days?
Oh also, it might work - Rescue Remedy is an all-natural miracle potion! I found the info on this site and have been so pleased with it! You can get it at vitamin shops or Whole Foods. It totally mellows her out!